72 MORPHOLOGY AND EVOLUTION
given by the rapidity and distance of her swinging leaps would seem to require a gradual abatement of her movements. In the very midst of her flight a branch is seized, the body raised, and she is seen, as if by magic, quietly seated on it, grasping it with her feet. As suddenly again she throws herself into action.
" The following facts will convey some notion of her dexterity and quickness. A live bird was let loose in her apartment; she marked its flight, made a long swing to a distant branch, caught the bird with one útand in her passage, and attained the branch with the other hand; her aim, both at the bird and the branch, being as successful as if one object had gained her attention.'7
" On another occasion this animal swung herself from a perch, across a passage at least twelve feet wide, against a window which it was thought would be immediately broken: but not so; to the surprise of all, she caught the narrow framework between the panes with her hand, in an instant attained the proper impetus, and sprang back again to the cage she had left, a feat requiring not only strength, but the nicest precision."
The progress of the Gibbons from branch to branch is carried out differently from that of the Monkeys. A Mangabey, for example, which has a long, non-prehensile tail, springs from branch to branch, using its hind limbs for propulsion and its tail for balancing. But the Gibbons employ their arms alone, the legs being tucked away close to the body, and out of the way of possible injury. The Orang-Outan, which is the most arboreal of the higher Apes, is not nearly so active as the Gibbons.
Considerable evidence has been collected to show that the Gibbons are the most bipedal of the Apes.